There is no correct answer.
A reverse flow smoker offers you the most even temperature across the firebox. It will not sear.
Any grill that can sear is only going to be as even as the coals you put in, and how you arrange it, bearing in mind, that the way heat behaves in a vertical column with sides is always going to give you a hot center and colder edges.
Smoking in a cabinet offers some variability from top to bottom, but, a properly designed cabinet gets very close to even temperatures.
Most people learn to use the variability in their cooker to their advantage.
I prefer a kettle or direct fire grill for searing, and for smoking, but, there is no unit I know of that does both well.
I'm feeling bearish, and I'm packing a Wusthof Grand Brisket slicer from MABA
"perhaps...but then again...maybe not..."